This section provides background information related to the present disclosure which is not necessarily prior art.
Due to increased demand for four-wheel drive vehicles, many power transmission systems are being incorporated into vehicle driveline applications for transferring drive torque to the wheels. In many four-wheel drive vehicles, a transfer case is installed in the drive train and is normally operable to deliver drive torque to the primary driveline for establishing a two-wheel drive mode. The transfer case is further equipped with a clutch assembly that can be selectively or automatically actuated to transfer drive torque to the secondary driveline for establishing a four-wheel drive mode. The clutch assembly can typically include multiple sensors that provide feedback to a controller to determine a particular drive mode.
In many examples, an actuator in the form of an electric motor is provided for influencing translation of a mode fork to change the drive mode between two-wheel drive mode and four-wheel drive mode. The four-wheel drive mode can result from meshing engagement of a pair of cooperating gears such as on a mode sleeve that moves in response to movement of the mode fork and a drive sprocket associated with the secondary driveline. Typically, the electric motor is configured for rotating in a first direction to influence the mode fork to translate in a first direction (such as for shifting from the two-wheel drive mode to the four-wheel drive mode) and configured to rotate in an opposite direction to influence translation of the mode fork in a second opposite direction (such as for shifting from the four-wheel drive mode to the two-wheel drive mode). In some examples, corresponding splines formed on the corresponding gears may not be immediately aligned during shifting between modes. In such a circumstance, continued rotation of one of the gears is necessary until a biasing member urges the shift fork into the engaged position. Therefore, it is typical to incorporate a first sensor that senses a motor position and a second sensor that senses a mode fork position. A need exists in the art to provide a simpler, more cost effective actuator that transfers drive torque between a two-wheel drive mode and a four-wheel drive mode.